Can I change an outdoor outlet from a standard plug in to a 30amp RV plug simply by changing the plug type & changing the breaker to 30 amp?
No. You will need to increase the size of your wire. Assuming the distance is short enough so that voltage drop isn't a problem, you will need at least 10AWG wire. Your standard outlet is most likely 12AWG or 14AWG, depending if it's on a 20A or 15A breaker.
You may want to have an electrian help you install this. Not knowing the wire needs to be changed along with the receptacle and breaker shows a lack of understanding in electrical work. DIY electrical work can be dangerous and should be done by those who are knowledgeable and qualified to work with electricity. Please know I'm not trying to burst your bubble or insult you. Safety is my number one priority and I wouldn't feel comfortable leaving this answer without this comment.
Breakers protect wires
The main purpose of a circuit breaker is to prevent wires from overloading, overheating and thus having dangerous problems like starting fires.
So your first step is to evaluate the size of the wire or cable. Wire size causes an absolute limit for breaker size that you cannot exceed:
- 14 AWG wire is limited to a 15A breaker
- 12 AWG wire is limited to a 20A breaker
- 10 AWG wire is limited to a 30A breaker.
You must use no larger a breaker than that, period. The good news is, this is enough to protect the wire from overheating. You don't have to think about the length of the circuit for this part.
Next, wire length
This is a matter of good practice rather than legal mandate. If your circuit is over about 75' long, voltage drop may become an issue at higher amp loadings. The important factor is how much current you are actually drawing in practice (not the breaker capacity rating). If your circuit is long, but in practice you simply aren't seeing voltage drop over about 3-5% (3.6-6 volts below normal), then don't worry about it.
Some people think you should downsize your circuit breaker to protect yourself from high voltage drop. I'd play it by ear. But with any luck, the guy who installed this wired it with 10AWG to compensate for the distance, and downsized the breaker to 20A "to protect himself from voltage drop". In that case, feel free to breaker to the spec limit of the wire, as discussed in part 1.
Receptacle must match breaker
Whatever breaker size you end up using, the socket must be the same ampacity. 15=15 20=20 30=30.
The only exception is if the circuit is breakered at 20A, two or more 15A sockets are allowed, but that works against your goal.
If you want to plug a TT30 into that, use an adapter cable. You won't be able to pull full amps, but it'll work.